This invention relates generally to a hose assembly employing a hydroformed fitting, and more particularly, to an improved hydroforming system and method of using a die to hydroform a hose fitting.
Hydroforming, sometimes referred to as fluid forming, was developed during the late 1940s-early ""50s in response to a need for a more efficient, cost-effective method of producing metal parts. As a general principle, hydroforming involves application of a predetermined fluid pressure to an area of metal surface to be manipulated. Where the metal surface is a tube, an internal fluid pressure is applied as the tube is bent and stretched. Generally, hydroformation of a tube can be accomplished by filling the tube interior with the fluid, retaining it therein and increasing the internal pressure. Depending upon the die tool utilized, hydroforming can also be used to radially expand the tube.
Specific advantages of hydroforming include: relatively inexpensive tooling, the availability of complex shapes and contours, minimal material thinout (hydroforming flows the metal rather than stretching itxe2x80x94thinout is usually less than 10%), reduced finishing costs (bid comparison, matched die methods of formation can cause scuff marks, shock and stretch lines), and precision with difficult configurations even where high tolerances are required.
Typically, fittings manufactured for use ill conjunction with hose assemblies are machined at considerable expense. Where a one-piece machined fitting is not available or is uneconomical, a brazing procedure can be utilized to provide the desired fitting from two components. Inherently, brazing provides a structural weakness which may manifest itself through failure upon application of routine pressure forces. Where one-piece fittings can be machined, they are difficult to bend if a curved configuration is required. Even so, bending introduces material weaknesses and increases the potential for failure at application pressures.
There are a considerable number of problems and deficiencies relating to the manufacture of hose fittings and, subsequently, assemblies with such fittings. The search for a cost-efficient and effective alternative to machining has been an on-going concern in the art. There is a need for a system/method, hose fitting and/or assembly which takes advantage of the manufacturing and commercial benefits typically associated with hydroforming.
It is an object of this invention to overcome the problems and shortcomings of the prior art, including those described above. Another object of this invention can be to provide a hose assembly prepared using a hydroforining process.
It can be another object of the present invention to provide a one-piece hose fitting which is formed unitarily, without brazing, to maintain structural integrity.
It can also be an object of this invention to provide a fitting meeting pertinent industry dimensional, design and/or performance specifications or their equivalents, such a fitting as can be hydroformed and/or used in conjunction with a hose assembly also meeting or equivalent to such underlying specifications.
It can also be an object of this invention to provide a system for hydroforming, unitarily, a one-piece hose fitting, such a system as can include a die tool and/or a set of dies, as can be used to hydroform a fitting meeting or equivalent to various industry specifications.
It can also be an object of the present invention to provide a system having an interchangeable die tool and/or dies such that hose fittings of variable design and dimension can be hydroformed from tubular stock.
It can also be an object of this invention to provide a system and/or method for hydroforming a hose fitting for use in conjunction with a securing mechanism, such that a hose can be assembled with such a fitting.
It can also be an object of this invention to provide a metallic hose fitting hydroformed such that the fitting is substantially free of machine lines, scuff marks and related surface deformities typically observed as a result of machining or related mechanical/grinding procedures, and substantially without material thinning, allowing for a degree of thinning inherent to hydroforming processes.
It can also be an object of this invention to provide a hose fitting, assembly, system and/or method obviating the need for costly finishing work on the hose fitting.
It will be understood by those skilled in the art that one or more aspects of this invention can meet certain objects, while one or more other aspects can meet certain other objectives. Each objective may not apply equally, in all instances, to every aspect of this invention. As such, the following objectsxe2x80x94in light of the prior art regarding hose assemblies, hose fittings and methods for their preparationxe2x80x94can be viewed in the alternative with respect to any one aspect of the present invention.
Other objects, features and advantages of the present invention will be apparent from the following summary and description of preferred embodiments, and as such, will be readily apparent to those skilled in the art having knowledge of various hose fittings, assemblies and the requirements for their use in trade and industry. Such objects, features, benefits and advantages will be apparent from the above as taken in conjunction with the accompanying examples, tables, data, figures and all reasonable inferences to be drawn therefrom.
This invention includes an improved hose fitting, as well as an assembly for use therewith, together with a system and/or method of preparing such. The invention overcomes certain well-known problems and deficiencies, including those outlined above, while providing a cost-effective alternative to current manufacturing and machining operations. In part, the present invention is a hose assembly, including: (1) a unitary hose fitting hydroformed from a tube and (2) a hose functionally and dimensionally compatible with the hose fitting. Consistent with die benefits available through hydroforming but heretofore unrealized in the context of a hose fitting, application of internal tubular pressure results in a number of structural characteristics not available through use of the prior art, including metal flow without stretching or substantially thinning the metal. In such a way, a one-piece fitting can be unitarily prepared without brazing and without lines or scuff marks or other surface imperfections typically resulting from a machining operation. At least a barb can be incorporated into the fitting configuration, such that the hose component mates with the fitting and engages a barb incorporated therein.
In preferred embodiments, the hydroformed hose fitting has at least one portion for attachment of a securing mechanism. In such an embodiment, the assembly also includes a mechanism to secure the hose to the fitting. hi highly-preferred embodiments and without limitation, the mechanism can be a ferrule or a clamp. While screw style fittings may be less preferred for certain assemblies or uses, such can also be hydroformed in accordance with this invention providing measures are taken to maintain structural integrity about the thread portion. See, for instance, U.S. Pat. No. 5,333,775 referenced below.
Likewise, ill preferred embodiments, the hydroformed fitting of die assembly has dimensional aid performance properties selected from, among other properties, dimensional and performance properties either meeting or equivalent to Society of Automotive Engineers (SAE) J516 standard specifications for hydraulic hose fittings. In a similar fashion, preferred embodiments of the present assembly include those where the hose component has dimensional and performance properties selected from those dimensional and performance properties either meeting or equivalent to SAE J517 standard specifications for hydraulic hoses. Such standard specifications for hydraulic hose and hose fittings, as well as other hose and fitting components, are well-known to those skilled in the art, but heretofore have not been utilized in conjunction with hose fittings, assemblies or their manufacture. Incorporation of such standard specifications will be well-known to those skilled in the art made aware of this invention.
The compatibility of the hose component with the inventive fitting of this invention can be in accordance with SAE recommended practice J 1273. In particular, pursuant to recommended practice under SAE J1273, die pressure of an assembly system must first be determined. Hose selection is then made so that die recommended maximum operating pressure is equal to or greater than die system pressure. Surge pressure higher than the maximum operating procedure will tend to shorten applicable hose life; accordingly, such pressures must be taken into account in determining compatibility. Other factors include, without limitation: suction (negative pressure), temperature of a fluid passed through the hose, fluid compatibility with the hose and fittings, size of the components as compared to the pressure and rate of flow of the pressurized fluid, the environment (ultraviolet light, ozone, salt water, chemicals, etc.) which can cause degradation, mechanical loads (induced by flexing, twisting, etc.), abrasion and electrical conductivity. Such factors and other related considerations are well-known to those skilled in the art and will be understood as applicable to the present hydroformed hose fittings and their use with hose assemblies, as those individuals are made aware of this invention.
Other preferred embodiments of the assembly of this invention include those where multiple barbs are provided on the fitting component. Such barbs can have a variety of configurations, including, without limitation, circumferential edges, squares, beads or a combination of such configurations. Likewise, in preferred embodiments, the fitting of this invention has a uniform wall thickness dimension. Even so, where variations are required, such can be introduced by hydroforming the fitting in accordance with the methods and procedures described in U.S. Pat. No. 5,333,775, the entirety of which is incorporated herein by reference.
In part, the present invention is an improved hydroforming system. The improvement includes a plurality of dies, but at least first and second opposed dies, removably engaging one another and defining a cavity for placement of tubular stock. Reference is made to several figures described below. Each die has at least one concave portion, and the concave portions are arranged to define a cavity having the design and outer dimensions of a hose fitting. in preferred embodiments, the dies are configured such that the cavity has a design and dimensions meeting SAE J516 standard specifications for hydraulic hose fittings, or a design and dimensions equivalent to such standard specifications. In highly-preferred embodiments, the cavity has a concave portion so as to provide a hose fitting with a configuration engageable with a ferrule. In a singular fashion, with or without such a configuration, a highly-preferred embodiment provides a cavity having a concave portion to provide at least one hose barb on die resultant fitting.
In part, die present invention is a method of using a die to manufacture a hose fitting. As described more fully above, such a fitting has a configuration suitable for use with a hose assembly. The inventive method includes: (1) providing a metallic tube, (2) providing a die tool to engage the tube and defining a shaped cavity, (3) contacting the interior of the tube with an expansive material and retaining the material within the tube, (4) increasing the pressure of the expansive material on the tube interior to a predetermined level sufficient to flow the metal component of the tube, and (5) engaging the tube with the aforementioned die tool to form a hose fitting.
As can be utilized with the present invention, a tubular blank is filled with a hydroforming fluid, by introduction to a fluid bath, injection or placement of the fluid therein. The ends of the tube can be plugged to retain the fluid within the tube, with the internal pressure thereafter increased to a desired level according to techniques known to those skilled in the art. Either sequentially or contemporaneously therewith, the die tool is brought into engagement with the tube to hydroform a hose fitting having an external configuration and set of outer dimensions defined by and/or corresponding to the shaped cavity. Mechanical and hydraulic components usable with the present method are well-known, as illustrated by the description provided in U.S. Pat. No. 5,471,857 which is incorporated herein in its entirety. Other such components or mechanisms can include a cam lock of the sort which could be arranged and configured to be used in conjunction with and/or close the dies of FIGS. 5B and 5C, as described below.
In preferred embodiments, engagement of the die tool with a pressurized tube provides a hose fitting with a design and dimensions selected from a group of properties meeting, SAE J516 standard specifications for hydraulic hose fittings or, without limitation, properties equivalent to such standard specifications. Alternatively or in conjunction therewith, the engagement results i a dimensional configuration providing a mating relationship with a ferrule.
The present method is described above in terms of utilizing a hydraulic fluid. In preferred embodiments, such a fluid is a hydraulic oil of the sort which can be used in hydroforming operations of the prior art. In other embodiments, various other expansive materials can be used, as would be well-known to those individuals skilled in the art mid made aware of this invention. Such expansive materials include, without limitation, water, urethane and an explosive. Regardless of the identity or nature of the expansive material, internal pressures of the sort useful with the present invention are preferably at least about 55,000 psi. However, pressures of from less than 5,000 psi to greater than 150,000 psi can be employed, depending at least in part on tubular material choice and desired outer diameter of the resulting hose fitting. Various other pressures and method parameters can be utilized, as required by the particular hose fitting hydroformed and as would be well-known to those skilled in the art having knowledge that such articles can be hydroformed.
The method of this invention can be utilized in conjunction with one or more of several additional related steps and/or processes. For instance, a metallic tube can be preformed or swaged, using al automated punch or one of several commercially available swaging machines. See, for instance, U.S. Pat. No. 4,662,841 which is incorporated herein in its entirety. Various resulting tubular configurations can result therefrom. In particular and as a preferred embodiment of this invention, a tubular portion eventually hydroformed to provide hose barbs can be preformed in this manner to provide a reduced outside diameter. Without limitation, reference is made to FIG. 6. The preformed and/or swaged tube of FIG. 6 can then be hydroformed as described herein to provide a hose fitting of the type shown in FIG. 7.
The method of this invention also contemplates one or more steps or processes after hydroformation. For example, the hose fitting of FIG. 1 can be machined or otherwise manipulated with respect to the portion preformed and/or swaged to widen the inside diameter, if required to improve fluid flow properties. Likewise, without limitation, the fittings of this invention can be heat-treated after hydroformation to improve various physical, structural and/or metallurgical properties.
Material expansion is a concern during hydroforming operations. Expansion is limited for a given tubular material having a given starting inner and outer diameters and a desired resulting outer diameter. Further expansion results in an undue material thinning and eventual failure at a certain application pressure. Such expansion and pressure limits can be determined experimentally or via computer simulation. For instance, for a tubular blank of 1010 steel material (0.75-inch diameter and 0.095-inch thickness), it was determined that die limit of outer diameter expansion is about 31%, beyond which there occurs deleterious material thinning. For example and using the above material specifications, a tube blank having a 0.75-inch outer diameter can be appropriately expanded to provide an outer diameter of about 0.984 inches. With respect to the present invention and, in particular with reference to FIG. 1, such an expansion and limit can be most pertinent to the formation of raised portions 12 and the mating relationship with a corresponding coupling mechanism (see, FIG. 4).